http://blog.csdn.net/lonely_fireworks/article/details/22291835http://www.cnblogs.com/henanjing/archive/2012/10/19/2730729.htmlhttp://www.taitaimao.net/mao.php?u=NUTd2Q5PmT2J4iNogjhfZxnmkR3jRWRUlePOmirM5CQdTP9dlVaHfEObywANZF2lwt8fxv10wMoSICmr&b=7